1. Field of the Invention
The present invention relates to a command input method using a three-dimensional motion recognition device embodied with an inertia system, and more particularly, to a command input method capable of increasing the total number of commands using a movement pattern as well as initial posture information in a motion recognition device.
2. Discussion of Related Art
Together with generalization of new, various digital media and appearance of various terminal devices compatible therewith, various input devices are being introduced and used. Existing portable input devices include a remote controller, a keyboard, and a mouse. However, the existing input devices are characterized by their complexity of use and restriction in a physical space, and thus the devices and/or their functions are being gradually replaced by new input devices. Such a phenomenon is remarkable, particularly, in a small-size terminal device.
Using one of input devices expected to substitute the existing input devices useful value itself, a study has been made of methods and devices for recognizing and analyzing the spatial motion of a user and giving a command to a target device.
There are various methods for detecting movement in a three-dimensional space. One of them is to photograph a moving object using a camera, and analyze movements by processing the object image. In this case, a plurality of cameras is required, and a user should use the object having a particular shape or color for the image processing. In addition, the image processing is complicated and has to be used in a restricted space. Thus, the method is inappropriate to be used as an input method of a portable device.
Another method uses a principle of triangulation. This method is to fix a device for transmitting/receiving a radio or ultrasonic wave instead of a camera at a specific position, measure variation of the radio or ultrasonic wave when a target device moves within the coverage of the transmitting/receiving device, and to trace the trajectory of the target object. This method is only possible when used in a restricted space, and it is difficult to be applied to cases involving minute movement.
For other methods, a device with an integrated inertia system is used. For concrete example, there are pen type pointing devices used to detect movements in a three-dimensional space using combination of a three-axis angular velocity sensor, a three-axis accelerometer, and a three-axis velocity sensor. Each of these devices is connected wirelessly to a computer, transmits variation of an angular velocity, which is caused by inclination and movement thereof, to the computer, and moves a mouse pointer of the computer or creates trajectory for handwriting recognition.
As another example, there is a pen type input device using a three-axis accelerometer and a three-dimensional optical recognition device. This input device determines the contactness of the device with a predetermined physical plane (e.g. a table) and an angle thereof, using the three-dimensional optical recognition device, and extracts trajectory based on movement of a pen by reflecting posture information of the measured device on acceleration information generated by movement.
As yet another example, there is a small-size ring type input device using a two-axis accelerometer. The input device measures an acceleration based on finger movement on a predetermined physical plane, and analyzes movement trajectory of a user. In other words, the input device detects a signal generated when a finger gets in contact with a predetermined surface and a signal generated when the finger leaves the surface using the two-axis accelerometer, double-integrates acceleration value of the signal duration therebetween, extracts movement trajectory of the finger, and uses extracted information as pointing information of a computer. This expansion makes possible application such as handwriting recognition.
The methods using the camera, the triangulation, and the inertia system commonly project the user's movement onto the trajectory of the two-dimensional plane, and have the projected trajectory correspond to motion of the control target. In certain cases, a physical two-dimensional plane is essential. Accordingly, it is possible to recognize less number of motions than the number of motions directly recognized in the three-dimensional space. Therefore, there is disadvantage in that the total number of available motions is remarkably reduced.
In the case where the number of the trajectories projected onto the two-dimensional plane is increased to overcome this limitation, the complexity and the total number of the trajectories are increased, thereby causing a limitation of making it difficult not only to embody an algorithm for trajectory recognition but also for the user to memorize the trajectories.
Accordingly, in the methods using the inertia system, there is disadvantage in that the complexity of the motion recognition is increased due to various correction techniques for increased accuracy of the final trajectory to facilitate the recognition process and for increased number of distinguishable motions, and due to the algorithm for the trajectory projection onto the two-dimensional plane. Due to the increasing complexity in motion recognition, there is a disadvantage in that a collection of the available motions should be minimized.